1. Field of the Invention
The invention relates to a device for cleaning large flat surfaces such as concrete flooring and roadways, and particularly for removing gravel and debris from a flat roof prior to resurfacing the same. More particularly, the invention relates to a device which applies high pressure streams of a fluid against the roof surface to loosen the gravel therefrom, and which then picks up the dirty fluid and loosened gravel from the roof by suction.
2. Description of the Prior Art
Many industrial and commercial buildings have flat roofs which are covered with layers of asphalt-saturated sheet materials that are laid upon the roof surface and cemented together. Additional coatings of asphalt or tar then are placed on the roof to form a waterproof covering for the roof. A layer of pea gravel and small rocks also is spread on the hot asphalt to provide a protective covering for the roof and saturated sheets against physical damage and weather deterioration. After a certain length of time, these asphalt/gravel roofs must be rehabilitated to prevent leaks since such roofs only have a limited life span.
The repair procedure or rehabilitation includes initially removing the gravel cover, much of which has loosened from the asphalt, together with all of the ambient dust and dirt which has settled on the roof throughout the years. After removal of the gravel, dust and dirt, a new layer of tar then is applied to the roof surface, with a new layer of gravel being placed thereon.
Removal of the old gravel and dirt from the roof is a difficult and time-consuming operation. One common procedure for removing these materials is by sweeping the roof with heavy brooms which takes considerable time and personnel to accomplish a satisfactory result. Also, dust and dirt are stirred up by the sweeping and gravel removal on the roof, which is objectionable to people in the vicinity of the building.
To overcome this problem, various sweepers and cleaning devices have been designed, which in addition to removing the gravel from the roof by a source of high suction, use streams of water sprayed against the roof during the removal process. This reduces the dust created by the sweeping action and assists in loosening the gravel and dirt from the roof. One example of such a system is shown in U.S. Pat. No. 3,955,236. This system, as well as other similar systems, consists of a remote unit located on the ground adjacent the building which produces a vacuum that is connected to a cleaning wand or machine movable over the roof surface. Also, in addition to applying the suction source, these units provide a source of high-pressure water to the cleaning head to facilitate removal of the gravel and dirt from the roof.
Further examples of various cleaning devices for cleaning roadways, pavements or other flat surfaces which use a cleaning fluid in combination with a source of suction for loosening and removing the dirt from the surface being cleaned are shown in U.S. Pat. Nos. 3,694,263, 3,837,038, 3,959,010, 4,107,816, 4,168,562, 4,191,590 and 4,219,155. Although these units and others similar thereto are believed to perform satisfactorily for their intended purpose, they do present certain problems and difficulties.
Many of these prior cleaning devices are large and bulky which makes it extremely difficult to transport them onto the roof of a commercial or industrial building for removing the gravel and dirt therefrom. These large units also are difficult to move across the roof and maneuver about the various ventilating ducts, pipes, air conditioning units and other obstructions on a roof.
These prior cleaning devices must be large in order to provide a sufficient suction force for removal of the gravel and dirt and to provide the high pressure for the cleaning fluid. Also, the known cleaning devices which use rotating spray nozzles require a separate motor for driving the spray nozzles, which increases the weight and size of the cleaning unit. Another problem with prior cleaning devices is that leaks commonly occur due to the high pressure of the cleaning fluid, especially in those devices in which the nozzles are rotatably mounted on the unit. It is difficult to achieve an efficient leakproof seal between the stationary components and the rotating nozzle rotor. Also, these prior devices require large vacuum-producing motors and compressors, which even if located on the ground adjacent the building, increases considerably the initial cost of the equipment as well as the power and energy requirements for operating the same. Another problem with these prior devices is that it is difficult to move these large units closely adjacent to the various obstructions on a roof in order to clean the gravel and dirt from the corners and edges along these obstructions. All of these factors increase the cost in order to provide an efficient cleaning job for a customer.
Therefore, the need has existed for a mobile device for cleaning large flat surfaces, and in particular for removing gravel and dirt from a roof to be resurfaced, which provides a large suction force with smaller equipment than heretofore possible, thereby reducing initial equipment cost and energy cost for operating the same, which enables a fluid to be sprayed onto the surface being cleaned under a relatively high pressure by providing an efficient seal and bearing unit for mounting the rotating nozzles, and in which the device is relatively lightweight and easily moved across the surfaces being cleaned. I know of no apparatus other than my cleaning device, which is described below, which achieves these results in as efficient and satisfactory a manner.